The field of art to which this invention pertains is moisture absorbent particles.
Moisture absorbent particles, such as those used as animal litter, have been made from moisure absorbent clay as described in U.S. Pat. No. 4,704,989. In this patent, clay fines are blended with an aqueous solution of lignin or lignosol and the mixture is converted into partially dried, multi-faceted, bulky aggregates through the action of a pin-type processor.
In U.S. Pat. No. 4,343,751, clay fines, either alone or combined with fly ash, paper sludge, sawdust, peanut shells and the like, are agglomerated into particles.
U.S. Pat. No. 4,591,581 describes a process for manufacturing moisture absorbent particles from clay fines and water dispersible additives having colloidal properties in water.
As described in U.S. Pat. No. 4,258,660, moisture absorbent pellets for use in animal litter have been made from bentonite clay binder plus finely ground straw.
A process for dewatering an aqueous dispersion of clay and agglomerating the clay into particles is described in U.S. Pat. No. 4,222,981. A hydrophobic organic bridging liquid and a liquid conditioner which is effective to displace water from the clay particles are added to an aqueous dispersion of clay. With agitation, the clay particles agglomerate, are separated from the water and dried.
In U.S. Pat. No. 3,935,363, flocculated clay mineral aggregates are used in water absorbing articles.
Moisture absorbent particles used in such applications as animal litter must be capable of absorbing aqueous liquid without fracturing and breaking up, must be able to withstand pressure while wet or dry without fracturing and must not become sticky so as to cling to the animal fur. There is a continuing effort to improve the overall performance of moisture absorbing particles, particularly the ability to absorb large amounts of water.